The violent and senseless death of 11-year-old Luke Batty in Victoria has not only drawn attention to the serious problem of family violence but has also raised questions about the role that undiagnosed or untreated mental illness may have played in his father’s behaviour.

The relationship between violence and mental illness is a vexed and contentious issue. The vast majority of people experiencing mental illness are not violent. However, those with a serious mental illness have increased rates of violence, including family violence, when compared to people who do not have a mental illness.

This fact is both distressing and unpalatable for people who experience mental ill-health in our community. It is also difficult for their families and friends, and for the advocates and health professionals who dedicate their careers to the mentally ill.

They know that an association with violence stigmatises a group of individuals who are already among the most disadvantaged in our society. It unnecessarily creates fear, especially when pejorative terms like “dangerous” are recklessly linked with mental ill-health.

Still, the fear of further stigmatising a disadvantaged group should not shut down a much more important conversation. If violence is related to some forms of mental illness, how can we better deal with this to prevent, or at least minimise, violent behaviour?

Despite the alarm that these figures might cause, this body of research also indicates that only a very small minority of those with mental ill-health ever commit violent offences. The overwhelming majority of people with schizophrenia - about 90% - have no convictions for violent offences.

It is important to be clear that mental illness does not appear to cause violence. There is currently mixed evidence about whether other, more common, forms of mental ill-health such as anxiety and depressive disorders are associated with violence.

Rather, the evidence indicates that, as a group, people who experience psychosis (which is characterised by a loss of reality, usually in the form of delusional thoughts or perceptual hallucinations such as hearing voices) are at increased risk of committing violent acts.

The reasons for this higher risk are not yet fully understood. Further research is needed to identify why, and under what circumstances, violence by those with mental ill-health occurs.

Is it just mental ill-health, or do other factors matter?

The research shows that the risk of violence among people with psychotic disorders is increased when they abuse substances or have a personality disorder. Both substance abuse and personality disorders are also major risk factors for violence in people without mental illness.

Furthermore, for many of the people with a psychotic illness who become violent, especially men, this occurs during the early phases of illness, often before treatment has been sought or provided.

These findings are critical because they provide opportunities to reduce the risks of violence and ideally prevent it. This is possible if individuals (and families) have access to early, effective treatment as soon as signs of mental ill-health begin to emerge.

They should also receive comprehensive mental health and related services that focus on other factors that increase a person’s risk of acting in a violent manner. These risk factors include substance use, violent attitudes and homelessness.

Moving towards balanced and sensitive public discourse

Only a minority of those with serious mental illness will ever act in a violent manner.AAP/Gary Sissons

The relationship between violence and mental ill-health is not simply a matter of scientific or clinical concern. It is a highly emotive, personal and political issue. We must acknowledge this and do better to balance the reality of evidence with the reality of lives.

The risks of creating fear and public unease via sensationalist media reporting are real. So too are the risks for people who experience mental ill-health of stigma and discrimination that flow from such reporting.

But we cannot afford to ignore or dismiss the empirical evidence. To do so is to forgo the opportunities to intervene and potentially prevent violence from occurring. There is still much to be learned in this important field.

Violent acts can have devastating impacts. The impacts affect not only the victim, but also the mentally ill “offender”, who will most often harm a loved one. The person may also be charged and convicted of a serious offence.

As we have noted, the overall risk of being harmed by a person with mental ill-health is low. However, the possible relationship between mental illness and violence can provide the opportunity for family and friends to understand that their loved one may be at heightened risk of acting violently when unwell. It provides another reason to encourage the person to seek help and treatment.

Balance requires us to place the link between mental ill-health and violence in perspective. Only a minority of those with serious mental illness will ever act in a violent manner. Most will not, particularly if they do not misuse substances and do not have a co-occurring personality disorder.

The only thing more horrifying than Luke Batty’s death would be for all of us to learn nothing and continue to ignore difficult, but potentially remediable, realities.